N-alkylidene and arylidene-n-alkoxy and alkenoxy-n-methylammonium salts



United States Patent Ofifice 3 178 467 N-ALKYLIDENE AN 1) AiRYLIDENE-N-ALKOXY AEfiQLKENOXY N ME [H YLAMMONIUM S Henry J. Gerjovich and Donald L. Smathers, Wilmington,

Del., assignors to E. I. du Pont de N emours and Company, Wilmington, DeL, a corporation of Delaware No Drawing. Filed Mar. 7, 1961, Ser. No. 93,849 1 Claim. (Cl. 260-456) This invention relates to the preparation of N,O- dimethylhydroxylamine and homologues and is more particularly directed to processes for making such amines beginning with an alpha substituted N-methyl nitrone. The invention is further directed to N-alphasubstitutedlalkylidene-N-R -oxy-Nnrethylammonium salts.

Processes of the invention can be illustrated generally in the following diagram:

1 OH3NO2 nitromethane reduce 2- CHaNHOH N -methylhydroxylamine C O i t 3 R r 1 alpha substituted e C=NCH3 N -ruethyl nitrone 1 2; 1 quaternization l 4 -e R 0 R N-alpha-substituted- I alkylidene- C=N- 0 H3 X- N- Rz-oxy-N-methylammonium salt J R\ R1 5 OHBNH 0 R2 N-methyl-O-Rr hydroxylarnine where R==hydrogen or an alkyl group of 1 through 4 carbon atoms,

R =hydrogen, an alkyl group of 1 through 4 carbon atoms, phenyl, tolyl, monochloro or dichlorophenyl, nitro phenyl or furyl groups, or R and R taken together=cyclohexyl or cyclopentyl rings,

R =alkyl or alkenyl groups of 1 through 4 carbon atoms,

X=alkyl sulfates of 1 to 4 carbon atoms, benzenesulfonate, toluenesulfonate, chloride, iodide, or bromide.

PRODUCTION OF THE NITRONE The nitrone employed as a starting material can be prepared in any convenient way. As illustrated above nitromethane can be reduced as by catalytic hydrogenation with a palladium on carbon catalyst and hydrogen gas under to 60 pounds per square inch gauge of pressure. An acid such as oxalic should be present to take up the N-methyl-hydroxylamine which forms as a product.

The N-methyl-hydroxylamine is freed from the acid by the addition of a. suitable base such as sodium hydroxide and is then reacted with the substituted carbonyl compound as shown above. The hydroxylamine is of course in aqueous solution as a result of the hydrogenation and the substituted aldehyde or ketone is simply stirred into it to produce the corresponding nitrone.

The aldehyde or ketone is determined by the R and R substituents to be present in the novel N-alpha-substituted-alkylidene-N-R -oxy-N-methylammonium salts of the invention. The aldehyde or ketone is regenerated in the process and is recycled. Additional aldehyde or 1(6- tone can be added as required to make up losses.

The particular ketone or aldehyde employed is unimportant in the processes of the invention. As will be 3,178,457 Patented Apr. 13, 1965 seen from the flow diagram above the aqueous cleavage separates out the ketone or aldehyde, whatever its character, and it does not enter into the final product produced. It is therefore quite unimportant in terms of the production of Nmethyl-O-R hydroxylamine what ketone or aldehyde is employed.

Ketones and ialdehydes which can be used, as indicated above, include the following:

The nitrone as produced can conveniently be isolated by extraction into a Water immiscible solvent for it such as chloroform, methylene chloride, triohloroethylene, tetrachloroethylene, toluene, or trichloroethane.

The product as thus prepared can be dried from the solvent or, as will become apparent below, further reaction can be conducted in the solvent.

PREPARATION OF N ALPHA SUBSTITUTED ALKYLIDENE N R -OXY N METHYLAM- MONIUM SALT According to the invention a nitrone of the type above described resulting from the particular ketone or aldehyde employed is quaternized by treatment under anhydrous conditions and at a temperature from 35 to C.

The quaternizing agents employed are those which have the structure R X where X has the value above described. Thus there can be used methylating agents such as dimethylsulfate, methylchloride, methyl iodide, methyl bromide, methyl benzenesulfonate, methyl paratoluenesulfonate.

Other quaternizing agents which can be employed include diethyl sulfate, dipropyl sulfate, dibutyl sulfate, allyl chloride, ally bromide, methallyl chloride, allyl benzenesulfonate, allyl toluenesulfonate, butyl benzenesulfonate, Z-butenyl benzenesulfonate, propyl toluenesulfonate.

The amount of the quaternizing agent will ordinarily be a molecularly equivalent to the nitrone. There is no advantage to using an excess but no great disadvantage. It is enough that approximately one mol be used.

Quaternization is conducted in a substantially anhydrous condition since any water present usually results in a loss of yield. The reaction can be conducted between the nitrone and the quaterniz-ing agent in a melted condition or the reaction can be conducted in a mutual solvent.

The solvents can be any of those mentioned earlier for the nitrone and additionally there can be used:

Benzene Carbon tetrachloride Xylene Chlorobenzene Dibutylether Dichlorobenzene Dioxane The amount of solvent is almost immaterial. Enough should be used to give a fluid system but no great excess should be used because of expense, both of solvent and handling equipment.

The quaternization can be conducted over a considerable range of temperatures from room temperature or slightly above up to the decomposition point of one of the components or the end product. Generally if the contents are to be molten, higher temperatures will be used up to 150 to even 200 C. and of course a quaternizing agent such as methyl chloride or another volatile material would not remain in the system unless it were contained under pressure.

It is preferred to employ somewhat lower temperatures ranging from about 35 to 110 C. and ordinarily a temperature as low as will give a reasonable rate of reaction is preferred.

It will be understood that the N-alpha-substitutedalkylidene-N-R -oxy-N-methylammonium salts will be those having the R, R and R substituents as above described in connection with the quaternizing agent and the aldehydes and ketones. Examples of such salts are given below:

( 1 N-benzylidene-N-ethoxy-N-methylammonium ethosulfate (2) N-methyl-N-(p-methylbenzylidene)-N-npropoxyammonium proposulfate (3 N-n-butoxy-N- (o-chlorobenzylidene) -N-methylammonium butosulfate (4) N-(p-chloro-u-methylbenzylidene)-N-methyl-N- vinyloxy-ammonium p-toluenesulfonate (5) N- (Z-furfurylidene) -N-methoxy-N-methylammonium chloride (6) N-allyloxy-N-(2,4-dichloro-a-ethylbenzylidene)- N-methylammonium bromide (7) N- (Z-butenoxy) -N-(m-chloro-a-propylbenzylidene N-methylammonium chloride (8) N- 3 ,4-dichlorobenzylidene) -N-methyl-N- propenoxyammonium benzenesulfonate (9 N-methoxy-N-methyl-N- (m-nitrobenzylidene) ammonium iodide (10) N-methyl-N-(o-methylbenzylidene)-N-isopropenoxyammonium o-toluenesulfonate 17) N- (3-hexylidene) -N-methyl-N-n-propoxyammonium p-toluenesulfonate l 8) Bis- (N-Z-hexylidene-N-methoxy-N-methylammonium) sulfate 19) N-cyclohexylidene-N-methoxy-N-rnethylammonium methosulfate (20) N-cyclopentylidene-N-methoxy-N-methylammonium iodide THE AQUEOUS CLEAVAGE It is remarkable that the N-alpha-substituted-alkylidene- N-R -oxy-N-methylammonium salts of the invention are readily split up by the simple addition of one or more molecular equivalents of water to produce N-methyl-O- R -hydroxylamines with concurrent regeneration of the carbonyl compound corresponding to the starting nitrone. These two can be separated in any convenient manner, examples of which will be given hereinafter. Thus they can be separated by extraction.

Sulfuric acid, hydrochloric acid, or another mineral acid can, if desired, be added to the water. It is thought that the acid keeps the amine in aqueous solution. The amount of acid can vary from 0.01 to 2 mols based upon the weight of amine.

The N-methyl-O-R -hydroxylamine compounds and more particularly N,O-dimethylhydroxylarnine can be converted to a desired urea by reaction with an appropriate isocyanate. Thus if a 3,4-dichlorophenylisocyanate is used with N,O-dimethylhydroxylamine one obtains l-(3,4-dichlorophenyl)-3-methyl-3-methoxyurea.

Other R -oxy ureas and especially the methoxyureas of US. Patent 2,960,534, issued November 15, 1960, to Otto Scherer and Paul Heller, can similarly be prepared using the appropriate isocyanate.

In order that the invention may be better understood reference should be had to the following illustrative examples:

Example 1 According to a preferred practice of the invention, N- benzylidene-N-methoxy-N methylammonium methosulfate is prepared and from it by aqueous cleavage there is prepared N,O-dimethylhydroxylamine according to the following scheme:

CHgNO: nitromethane .1. reduce CHaNH OH N-rnethylhydroxylamine aipha-phenyl-N- methyl-nitrone 1 (CH3)1SOA aqueous cleavage l ono (m-methylbenzylidene) OH NHO CH: N, O-dimethylhydroxyl- Sixty-one parts by weight of nitromethane and 63 parts by weight of oxalic acid dihydrate and 6 parts by weight of 5% palladium on activated carbon catalyst and parts by weight of water are charged into a pressure vessel. The vessel is sealed and hydrogen is introduced to a pressure of 60 pounds per square inch gauge. As the vessel is shaken there is a slight temperature rise. The hydrogenation is continued until about 4 parts by weight of hydrogen are absorbed.

The vessel is vented and the vessels contents are filtered to remove the catalyst and transferred to a vessel equipped with a stirrer.

Forty parts by Weight of sodium hydroxide as a 50% aqueous solution is added and stirred into the product. It is preferred not to permit the temperature to rise in the stirred vessel to a high 'figure and should be kept can then be returned to the reaction. The remaining aqueous solution is adjusted to pH 6-7 and the amine is recovered by distillation.

Ex 1 l 2 below, say, 30 C. though this is not critical. Particular- 5 an p e 1y if solid sodium hydroxide is used there is a con- One hundred thlrty-five parts y w g t of a ph siderable tendency for the temperature to rise. p y y 100 Parts y Weight of Eighty-five parts by weight 'of benzaldehyde is added cblorobenzene, and 60 parts y welght of methyl @1110- and the mixture is stirred for about ten minutes. At T 1de are Charged 3 165561 fil p for P p this tim th re tio i essentially l t tron. The vessel is sealed, the temperature 1s raised to The reaction mixture is successively extracted with 4 and d r t ee rs. The vessel is cooled aliquots of chloroform each of which is about oneand l The p If not already Crystalline, 1S fourth the volume of the solution being treated. The Crystalhzed y coollng and scratchmg and then recovered combined chloroform extracts are dried over sodium y i y y- Y sulfate and evaporated to dryness. The product thus ammonium 0111010516 thus Produced can be hydrolyzed 1n produced is the nitrone shown above in Formula 3. the manner descflbed In Example 1 to Produce N,O-d1- methylhydroxylamine.

QUATERNIZATION OF THE NITRONE Example 3 ressures?death: 13; 22: B by of weight th nitrgne re ared as abov The methyl nitrone and 126 parts by weight of dimethylwariled radeu n n S Solution .g' 3 sulfate are mixed and held at 45-50 C. for one hour. tern eratl lre rise: The te erature is raised to itboui The N isoprOpy1idene-N methOXy N-methylammonium mp methosulfate thus produced is crystallized by cooling and 75 C. It is to be noted that as the product forms the 5 Scratching 2 iihi gg ii gg gg E 2323 32 Two hundred thirteen parts by Weight of the product is continueed Th nsolufion then nowzd c 01 treated with an equal weight of water containing 5 parts The re'sulti 6 Solution i chinaed and th S81 i H 80 by weight at C. for one-half hour. The rescr tch d o g to rzmote c stallizagon sulting clear solution is adjusted to pH 67 and N,O-dia -roductis fi Se aragd and ca b r g 30 methylhydroxylamine is distilled out first, followed by 2 kepk' dry e p p n e 0 e the acetone. The latter is then recycled. The yield based on the nitrone is substantially 100%, E mpl s 4 through 23 malor loss being matenal retained on the In the following examples a nitrone with the designated eqmpment' R and R substituents is prepared using an aldehyde or ketone with corresponding R and R groups. A quaterniz- THE AQUEOUS CLEAVAGE ing agent R X is employed as set out in the table below 100 parts by weight of the product prepared as above where the values of R, R R and X are tabulated. is treated with an equal weight of water at C. The The N alpha-substituted-alkylidene-N-R -oxy-N-methylwater contains sulfuric acid in the amount of 15 parts 40 ammonium salt is produced at the temperaures and times H by weight. listed and having the appropriate R, R R and X values The solution as produced is extracted with twice lts and then by aqueous cleavage there is produced an N- volume of toluene to remove the benzaldehyde. This methyl, O-R -hydroxylamine.

R R1 R2 X Quaternizing conditions N-Methyl-O-substituted hydroxylamine Phenyl Hydrogen... Ethyl Ethosuliate 80 0.;%hour; no solvent.. N-Methyl-O-ethyl-hydroxylamine. p-Tolyl -.do n-Propyl Proposuliate C.;%hour;dioxane N-methyl-O-nrosolvent. pylhydroxylamine. o-0hlorophenyl do n-Butyl Butosulfate.-. 0.; lhour; toluene N-methyl-O-n-butyl s vent. hydroxylamine. p-0hlorophenyl Methyl Vinyl p-Toluene-sulfonate. 60 0.;3hours; chloroform N-methyl-O-vinyl solvent. hydroxylalnlne. Z-furyl Hydrogen..- Methyl Chloride 140 0.; 3% hours; xylene O-N-dimethylsolvent. hydroxylamine. 2,4-dichloropheny1 Ethyl Allyl Bromide 30 0.; 10 hours; carbon N-methyl-O-ally1- tetrachloride solvent. hydroxylamine. m-Chlorophenyl Propyl 2-butenyl.. Chloride 60 0.;2hours;tetraehloro- N-methyl-O-(2-butenyl)- ethylene solvent. hydroxylamine. 3,4-dichlorophenyl Hydrogen..- Propenyl Benzenesulionate.-. 40 0.;8hours;methylcne N-methyl-O-propenylchloride solvent. hydroxylamine. 12 m-Nitrophenyl dn Methyl Iodide 84 0.; 5hours; O,N-dimethylt-richloroethylene solvent. hydroxylamine. 13 o-Tolyl do Isopropenyl.-- o-Toluenesullonate. 74 0.;2hours; N-methyl-O-isopropenyltrichloroethane solvent. hydroxylamine. 14 p-Nitrophenyl .-do is0-Propyl.- Iodide 0.;4hours; xylene N-methyl-O-lso-propylsolvent. hydroxylamine. 15 m-Tolyl do seeButyl. Bromide 142 0.; 3hours; dibutyl- N-methyl-O-sec-butylether solvent. hydroxylamine. Phony] Methyl iso-Butyl-- Chloride 135 0.;5hours;chlor0- N-methyl-O-iso-butylbenzene solvent. hydroxylamine. Hydro en Butyl Methyl Methosulfate 40 0.;2 hours; no solvent... O,N-%1imethylhydr0xylam e. Methyl Methyl -.do Iodide 80 0.;5hours; benzene O,N-din1ethylhydroxylsolvent. amine. Ethyl ....-do Ethyl Bromide 38 0.;8hours; no solvent.-- N-methyl-O-othylhydroxylarnine. 20 Propyl Ethyl n-Propyl p-Toluene- 60 0.; 3hours; chloroform N-methyl'O-n-propyL sulfonate. solvent. hydroxylamine. 21 Butyl. Methyl Methyl Sulfa 45 0;.4hours; no solvent... O,N-dimethylhydroxylamine. 22 Pentamethylene. do Methosullate 60 0.;%hour; no so1vent.. O,N-di.methy1hydroxyl- 31131116. 23 Tetramethylene -..do Iodide 100 0.; 4 hours; dioxane O,N-dimethylhydroxylsolvent. amine.

7 The claim is: A quaternary ammonium salt:

R on, oa r-ona] X- where R is selected from the group consisting of hydrogen and an alkyl group of 1 through 4 carbon atoms, R is selected from the group consisting of hydrogen, an alkyl group of 1 through 4 carbon atoms, phenyl, tolyl, mono-, and dichlorophenyl, nitro phenyl and furyl groups,

and R and R taken together equal cyclohexyl and cyclopentyl rings,

R is selected from the group consisting of alkyl and alkenyl groups of 1 through'4 carbon atoms,

X is selected from the group consisting of alkyl sulfates of 1 to 4 carbon atoms, benzenesulfonate, toluenesulfonate, chloride, iodide, and bromide.

References Cited in the file of this patent UNITED STATES PATENTS FOREIGN PATENTS Germany Jan. 8, 1959 OTHER REFERENCES Reiber et al.: I.A.C.S., volume 62, pages 3026-3030 Feely et al.: J.A.C.S., vol. 81, pp. 4004-4007 (1959). Knoevenagel: Ber. Deut. Chern., vol 54, pp. 1722-1730 Nerdel et al.: Ber. Deut. Chem., vol. 86, pp. 1005- 20 1010 (1953). 

